This application is a National Stage Application of International Application PCT/JP98/02540, with an international filing date of Jun. 8, 1998, the disclosure of which is incorporated into this application by reference.
The present invention generally relates to a non-contact IC card. More specifically, the present invention relates to a non-contact type IC card without a power supply source for transmission/reception of an electric signal to/from an external data processing apparatus by converting a radio wave received by a self-contained antenna coil to electric power.
A non-contact type IC card has been proposed and recently used which is provided with a semiconductor integrated circuit device (IC) for storing information (data) and transmits/receives information to/from an external data processing apparatus which utilizes or supplies the information in a non-contact state.
Such non-contact type IC card is used, for example, as a pass of the ski lift, a commuter""s pass for a train or bus, a tag for administration of inventory and the like, in an information management system.
In the information management system using the non-contact IC card, information is transmitted by an electromagnetic wave (hereinafter referred to as an RF carrier). An external apparatus modulates the RF carrier and transmits a command or information. The IC card is provided with a tuning circuit including a coil as an antenna for receiving the modified RF carrier and a capacitor.
The IC card demodulates the modulated RF carrier transmitted by the external apparatus for obtaining the command or information and, changes an impedance of the tuning circuit by a signal representing information to be returned in a period during which RF carrier is not modulated. The change in the impedance modulates the RF carrier. The external apparatus receives and demodulates the modulated RF carrier to obtain information from the IC card.
Preferably, the IC card can semi-eternally be used and thin. Thus, the IC card receives electric power from the RF carrier rather than having a power supply source with a limited lifetime.
Transmission of information and supply of electric power can be performed by the same RF carrier. When transmission of information and supply of electric power are performed by the same RF carrier, one tuning circuit is provided in the IC card. When transmission of information and supply of electric power are performed by different RF carriers, two tuning circuits are provided in the IC card. FIGS. 7 and 8 are diagrams showing conventional IC cards.
Referring to FIG. 7, an IC card 100 is provided with an IC chip 111, one tuning circuit 114, and a capacitor 115 for storing (smoothing) electric power obtained by an RF carrier.
Tuning circuit 114 is connected to IC chip 111. Tuning circuit 114 has a coil 112 as an antenna for receiving the RF carrier, and a capacitor 113 for resonance connected in parallel with the coil. Capacitor 115 is also connected to IC chip 111.
In such IC card 100, information is transmitted and electric power is supplied from an external apparatus to tuning circuit 114 including a coil 112 and capacitor 113. The supplied electric power is stored in capacitor 115 through IC chip 111.
Referring to FIG. 8, an IC card 200 is provided with an IC chip 221, two tuning circuits 224 and 229 and a capacitor 225 for storing (smoothing) electric power obtained by an RF carrier. Tuning circuit 224 has a coil 222 as an antenna for receiving the RF carrier, and a capacitor 223 for resonance connected in parallel with coil 222. Tuning circuit 224 is supplied with electric power from an external apparatus by receiving the RF carrier.
Tuning circuit 229 has a coil 227 as an antenna for receiving the RF carrier, and a capacitor 228 for resonance connected in parallel with coil 227. Coil 227 of tuning circuit 229 receives the RF carrier for data transmission with respect to the external apparatus.
Tuning circuits 224 and 229 and capacitor 225 are connected to IC chip 221. When tuning circuit 224 is supplied with electric power from the external apparatus, the electric power is stored in capacitor 225 through IC chip 221.
FIG. 9 is a plan view showing the IC card in FIG. 7, and FIG. 10 is a cross sectional view taken along the line Bxe2x80x94B in FIG. 9. Referring to FIGS. 9 and 10, IC card 100 is provided with a substrate 110, a coil 112, an IC chip 111 as a semiconductor device and capacitors 113 and 115. Coil 112 of a conductor is formed on substrate 110. Coil 112 has a coil outer end 112a and a coil inner end 112b. 
IC chip 111 as a semiconductor device is formed above substrate 110. IC chip 111 has a main surface 111c facing substrate 110. Main surface 111c has terminals 111a and 111b. Terminal 111a is electrically connected to coil outer end 112a. Terminal 111b is electrically connected to a coil inner end 112b which is on the inner side 112c of the coil by an interconnection 153 via through holes 151 and 152 formed in substrate 110.
IC chip 111 is electrically connected to capacitors 113 and 115 which are on the outer side 112d of the coil by an interconnection 157. A thin plate of resin (not shown) is formed on substrate 110 to cover coil 112, IC chip 111, capacitors 113 and 115 and the like. It is noted that inner or outer ends of two coils 222 and 227 are connected to a terminal of IC chip 221 via a through hole formed in the substrate and a back surface of the substrate also in IC card 220 having two tuning circuits 224 and 229 shown in FIG. 8.
In IC card 100 having the above described structure, terminal 111b and coil inner end 112b are electrically connected by interconnection 153 via through holes 151 and 152. Thus, interconnection 153 is not brought into contact with coil 112 except at coil outer end 112b or with capacitors 113 and 115. Therefore, a problem associated with a short-circuit is prevented.
However, such IC card 100 requires a step of forming through holes 151 and 152 and a step of forming interconnection 153 on the surface opposite to that at which coil 112 and IC chip 111 are formed. Further, a step of filling through holes 151 and 152 with metal for interconnection by vapor deposition is required. This makes a manufacturing process complicated and undesirable in terms of efficiency and cost.
As IC card 100 is thin and flexible, interconnection 153 is likely to be broken in through holes 151 and 152, thereby causing malfunction.
It is noted that although IC chip 111 is provided on the outer side 112d of the coil in IC card 100 shown in FIG. 9, IC chip 111 may be provided on the inner side 112c of the coil. However, also in this case, a through hole must be formed to electrically connect coil outer end 112a and terminal 111a of IC chip 111. As a result, the problem associated with the complicated manufacturing process and malfunction is caused.
To solve these problems, main surface 111c of IC chip 111 with terminals 111a and 111b may be formed as an upside in FIG. 10, where terminals 111a and 111b are electrically connected to coil outer and inner ends 112a and 112b by bonding wires, respectively. Such structure eliminates the need for a through hole and the manufacturing process is not complicated.
However, the bonding wire electrically connecting terminal 111b and coil inner end 112b crosses over coil 112, and therefore the bonding wire may be brought into contact with coil 112 and causes malfunction. Further, as a length of the bonding wire connecting terminal 111b and coil inner end 112b is large, external force may break the wire to cause malfunction.
Therefore, the present invention is made to solve the aforementioned problems. An object of the present invention is to provide a non-contact IC card which can readily be manufactured and is capable of preventing malfunction.
A non-contact IC card according to the present invention is provided with a substrate, a conductive layer provided on the substrate to form a coil, and a semiconductor device electrically connected to the conductive layer and having a main surface. The semiconductor device has first and second terminals formed in the main surface. The conductive layer has a coil inner end electrically connected to the first terminal and a coil outer end electrically connected to the second terminal. The semiconductor device is formed above the conductive layer such that the coil inner end is positioned in vicinity of the first terminal and the coil outer end is positioned in vicinity of the second terminal.
In the non-contact IC card having the above described structure, as the coil inner end is positioned in vicinity of the first terminal and the coil outer end is positioned in vicinity of the second terminal, a contact hole is not required for electrically connecting the end of the coil and the terminal of the semiconductor device as in the conventional case. Thus, the manufacture is facilitated and breakage of a wire is prevented. In addition, as the coil inner end is positioned in vicinity of a first terminal and a coil outer end is positioned in vicinity of the second terminal, even when the terminal and the end are connected by a bonding wire, the length of the bonding wire is small. As a result, breakage of the wire and contact of the bonding wire with the coil are prevented. Therefore, a non-contact IC card capable of preventing malfunction is provided.
Preferably, the semiconductor device is provided above the conductive layer such that the first terminal is positioned above the coil inner end and the second terminal is positioned above the coil outer end. Preferably, the semiconductor device is positioned to cover a portion of the conductive layer.
Preferably, the main surface of the semiconductor device has first and second corners, where the first and second terminals are respectively formed at the first and second corners. In this case, the conductive layer of the coil can be formed between the first and second corners. Then, the number of turns of the coil increases and, even when an intensity of an RF carrier is low, a signal or electric power can surely be obtained by the RF carrier.
Preferably, the first and second corners are spaced by a distance on an imaginary diagonal line on the main surface. In this case, the distance between the first and second corners is further increased so that the number of turns of the coil further increases.
The main surface of the semiconductor device with the first and second terminals may face the conductive layer. Preferably, the first terminal and the coil inner end are electrically connected by a solder and the second terminal and the coil outer end are also electrically connected by a solder. Preferably, each of the first and second terminals is in a bump shape. In this case, it is ensured that the first terminal and coil inner end are connected by a solder and the second terminal and the coil outer end are connected by a solder. As a result, the problem associated with breakage of the wire or short-circuit is not caused, so that malfunction is prevented.
The surface opposite to the main surface of the semiconductor device with the first and second terminals may face the conductive layer. Preferably, the first terminal and the coil inner end are electrically connected by a conducting line, and the second terminal and the coil outer end are electrically connected by the conducting line. In this case, it is ensured that the first terminal and the coil inner end are connected by the conducting line and the second terminal and the coil outer end are also connected by the conducting line. A length of the conducting line is smaller. As a result, the problem associated with connecting failure or short-circuit is not caused, so that malfunction is prevented.
Preferably, the semiconductor device and the coil inner end of the conductive layer are electrically connected by a composite material including an insulator in which a plurality of conductors are formed in one direction. The semiconductor device and the coil outer end of the conductive layer are electrically connected by the composite material.
Preferably, the non-contact IC card is provided above the substrate and further includes a capacitor connected to the semiconductor device.
Preferably, the conductive layer forms a plurality of coils.